There are compelling theoretical reasons to study the viral and immune response in the gut-associated lymphoid tissue (GALT) in HIV-infected individuals who have been treated with antiretroviral medication. The GALT contains approximately 50% of the lymphoid mass in the body, it serves as the site of initial HIV inoculation in many patients, and the vast majority of the lymphocytes in the GALT express memory phenotypic markers (e.g., CD45RO) and are chronically activated, which enhances HIV infection of these cells. We will evaluate the decay cells infected with HIV as well as trapped HIV in the FDC-network in this body compartment in the face of potent combination antiretroviral medication. We will also evaluate the repopulation rate of CD4+ lymphocytes in the GALT that may occur prior to their repopulation in the peripheral blood.